The Rocket Stove is a variety of wood-burning cooking stove. It is easy to construct, with low-cost materials. These are low-mass stoves designed to burn small pieces of wood very efficiently. Cooking is done on top of a short insulated chimney. The stoves are typically constructed out of trash: tin cans, old stovepipes, etc. A skirt around the pot will help hold heat in, increasing the efficiency.

Rocket Stoves use branches, twigs, small wood scraps, or just about any small combustible material. The pieces of wood or other material burn at their tips, increasing combustion efficiency, creating a very hot fire, and eliminating smoke. The low-mass stove body and insulated chimney ensure that the heat goes into the cooking pot, not into the stove. Rocket stoves used in conjunction with hayboxes can save enormous amounts of fuel, cooking complete meals while using very few resources.

A related design, the Rocket Bread Oven, is constructed using two 55 gallon drums, one inside the other. The outer drum is split open to create an insulated chimney space between the two drums and to allow for a doorway. Baking is done inside the inner drum--in a sealed compartment within the chimney, above the firebox.

Rocket Stoves operates roughly twice as efficiently, and substantially more cleanly, than the open fire cooking methods still used in many areas of the world. Furthermore, the design of the stove requires small diameter lengths of wood, which can generally be satisfied with small branches. As such, sufficient fuel for cooking tasks can be gathered in less time, without the benefit of tools, and ideally without the destruction of forested areas.

Because these qualities improve local air quality, and discourage deforestation, the rocket stove has attracted the attention of a number of Appropriate Technology concerns, which have deployed it in numerous third-world locales (notably, the Rwandan refugee camps). This attention has resulted in a number of adaptations intended to improve convenience and safety, and thus the size of the target audience. The Justa Stove, for example, is a cousin of the rocket stove adapted for indoor use and family cooking needs.

Contents

Key features

Fuel magazine - a short length of steel or ceramic pipe fitted horizontally into the base of the chimney

Fuel shelf - holds the fuel clear of the bottom of the magazine to allow air to flow underneath

Chimney - a metal box (such as a 5-gallon tin can) or pipe standing vertically and supporting the cooking vessel

Heat exchanger - a tubular metal shield that forces hot gases from the chimney to pass over the sides of the cooking vessel

Problems

Overview: Fire based solutions, such as the Rocket Stove, allow cooks to make meals when the sun isn't shining or achieve temperatures that would be difficult without expensive parabolic cookers. However, they do have drawbacks:

Pollution When biomass, such as wood, is consumed completely in the burning process, it produces carbon dioxide (C02) and water vapor (H20) alone. However, according to Joel S. Levine of the Atmospheric Sciences Competency NASA Langley Research Center in Hampton, Virginia, '[s]ince complete combustion is not achieved under any conditions of biomass burning, other carbon species, including carbon monoxide (CO), methane (CH4) nonmethane hydrocarbons (NMHCs), and particulate carbon, result through the incomplete combustion of biomass material. In addition, nitrogen and sulfur species are produced from the combustion of nitrogen and sulfur in the biomass material.' Further, it is possibly the most injurious common form of generating heat in terms of particulate emissions and other pollutants. The Union of Concerned Scientists give wood burning an environmental rating of 21,000 per dollar of expenditure for common pollutants and 27,000 per dollar for toxic pollutants. By comparison, solid waste disposal, the next highest rated group, resulted in numbers of around 1400 and 300 respectively for the same categories.

Efficiency The book, "Capturing Heat II" by the Aprovecho Research Center suggests that without a skirt the Rocket Stove is only about as efficient as a well-run open fire. With the addition of a skirt that efficiency rises, but is still less than the 40% that is sometimes cited.

Maintainability Tin can stoves that this author has purchased or made have disintegrated due to rust after 3 to 6 months. Its possible to build longer lasting ones by surrounding the internal cans with a mix of sand and clay but of course that means that the stove will have a higher thermal mass resulting in greater fuel usage.

Alternatives/Variations

Sierra Zip Stove

An interesting alternative -- at least in the developed world -- is the Sierra Zip stove. By pumping heated air into the combustion chamber quick high temperatures can be achieved with little energy wasted on thermal mass or warm-up time. Ensconced in a cooking system which skirts the cooking vessel, 4 oz of wood will give 2-3 minutes of gas-like cooking.

Two-Door Rocket Stove

The Two-Door Rocket Stove can burn both wood and charcoal. It saves a lot of both!
Wood fuels are fed into the big door. The small lower door controls the flow of air into the fire which lowers emissions. When burning charcoal, the big door is closed, and the rate of burn is also controlled by opening and closing the lower door.

Adding adjustable doors to a Rocket stove allows for control of the air that enters the fire to speed up or slow down the rate of combustion. More air is needed to start a cold fire and to create a hot fire initially. Once the fire is going, the bottom door is partially closed. Limiting the air increases heat transfer to the pot and reduces harmful emissions.

Carbon monoxide is reduced when it is burned up in the enclosed space above the fire. Frequently, enough charcoal is made when burning wood so that simmering can be done using only the made charcoal. After boiling food, the big door is closed and air from the lower door keeps the made charcoal burning. The interior grate and dual doors make the GreenFire Two-Door Rocket stove slightly more expensive than the one door stove.

Dimensions: Stove D-11 in H-11 in (Dimensions above are as packed for shipment) Upper Door: W-4 3/4 in H-2 3/8 in Lower Door: W-2 3/8 in H-1 1/8 in

Wood Pellet Camp and Survival Stove

Another new alternative biomass type outdoor cooking stove will be available by summer, 2008 called the Wood Pellet Camp and Survival Stove, from ClearDome Solar Thermal It is very clean and hot burning, also burns dried bamboo, twigs and branch parts, even peanuts and sunflower seeds! It weighs about 2 pounds and is easy to transport and use. Wood pellets are carbon neutral and very inexpensive- it's a dry fuel product with very little pollution. Unlike other small pellet cook stoves, no fan or external power is needed to generate 1500+ degree F temperatures, hotter than a conventional stove for short cook times. The photo shows the 5" x 7" tall pellet cooker on the beach at sunset.

Audio and video

How to Make a Tin Can Rocket Stove

How to make a 16 brick rocket stove

How to make a rocket stove from vermiculite

Articles in the media

February 2011: Aprovecho Research Center's Rocket stoves This article recognizes the Aprovecho Research Center for 35 years of work on Rocket Stoves, and notes worldwide initiatives to fund and develop fuel efficient stoves. - The Oregonian

The Institutional Rocket Stove Design Tool allows you to produce detailed designs for three different types of institutional rocket stoves. You specify pot and material dimensions, and the tool generates a custom set of Rocket Stove plans.